The Backlight Scanner is a photography tool that shields the light from your flashlight from the camera, while making sure you stay in the dark. The idea came from light painter Palateth (check his video on youtube:
This version of the Backlight Scanner is 3d-printed with PLA and was designed in SketchUp. You'll find both files for the top and bottom cone attatched.
Ø10mm round neodymium magnets
two-part epoxy or other strong glue
matte black paint
silver or chrome effect paint
sandpaper of various grits
3d-printer of access to a makerspace or FabLab.
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Step 1: Check the Diameter of Your Flashlight
This file was made to fit my Fenix and Thrunite flashlights with a similar diameter front. However the flashlight didn't quite fit after printing and the space had to be sanded away a bit. Make sure to edit the top of the Backlight Scanner to fit your flashlight.
Step 2: Print Both Files
Print both files or have them printed. 15% infill is plenty sturdy. If you have a choice, go with black filament, since you'll be needing less paint later.
Avoid supports at the inner part of the small cone and the outer part of the large cone, as these will be the light reflectors and need to stay as smooth as possible.
Step 3: Glue the Magnets
The magnets will hold everything together, while making it possible to detach both parts during transport. I went for 10mm neodymium magnets and they are plenty strong. I used two-part epoxy.Make sure to note the polarity and attach magnets with the same polarity on each side of the Backlight Scanner!
Step 4: Paint, Sand, Paint, Sand, Paint....
Now it's time to sand the pieces and put down a layer of primer. Our goal is not to erase all printer lines, but to make sure no light shines through the cones. Printing everything in black PLA definitely helps here. You'll want the parts that'll be painted silver as smooth as possible. The parts that will be black can keep their printer lines. The printer lines might even help to keep the reflections to a minimum.
Step 5: Paint It Black...
Paint everything black
Step 6: Masking and Silver Paint
Mask of everything that needs to remain black and paint the inner small cone and a part of the outer large cone silver or chrome. The shinier the better. Your finished paint job should look something like this.
Step 7: Try It Out
Attach your flashlight and have fun photographing.
With a bit of practice you'll be able to bring light to the darkness and make images like this one.
A guide on how to use the Backlight Scanner can be found at http://lightpaintingblog.com/light-painting-diy-t... and in the video above by Palateth.
All credits for the idea go to Palateth